what 280zx 5 speed

[Hello710]

would fit an l20b?that way i know what to look for?

[datzenmike]

They all will! The turbo FS5R90A and the non-turbo FS5W71B wil fit the L20B motor. In the case of the pig heavy turbo 5 speed I don't see why anyone would want to though, so that leaves the FS5W71B. Depending what you want you could also use the earlier 280z, the 620 truck or the later '79-'84 Maxima 5 spd. as well. They were all FS5W71B transmissions, just with different ratios.

[Hello710]

oh so what would be the best ratio foor lets say an autocross or somethin?

[datzenmike]

Well if strictly just chasing around cones in a parking lot you don't even need a 5 speed as you would never use 4th or 5th anyway. The only advantage is the 5spd would be stronger. As far as gearing, the rear end ratio could be changed to 4.11 from a first year 710 automatic and tire size (diameter) selected to fine tune for track conditions. I would avoid the 'wide(er) ratio' tranny gear set as first is too low for use if running a low gear rear end and small tires. There would also be a large drop in RPMs shifting to second. This would leave the 2nd to 3rd and the 3rd to 4th shift for much of the driving. 5th gear would just be along for the ride and is unimportant. If running stock 3.70 rear end and tires then possibly a 'wide ratio' tranny from the '79 620 truck may have a slight advantage. This would allow a quicker take off acceleration from start or in very slow corners. A word of caution here: a very fast car or one with gears may be too fast to use 1st gear in any of the corners so like 5th gear, it would be along for the ride for most of the race.

 

Some common 5 spds. with 3.321 first gear ratios are the '77 and '78 620 truck, the '77-'78 280z car and the '79-'84 Maxima with gas engine. Other than some of the switches these transmissions are the same. The '79 620 uses a 3.594 first gear and could be considered a 'wide ratio' compared to the other years. The '79 and on 280zx (non turbo) uses two different 5spds, but the bottom 4 gears are almost identical so I'll cal them the same. Both have the 3.321 first gear and I would basically lump them with the others. 5th gears are totally different but you aren't using them anyway. One advantage of the later zx 5 speed is the taller over drive 5th gear. It gives good hghway economy if the car is modified.

 

If hill climbing I would use any of these 5 speeds but the 'wide ratio' from the '79 truck. In all cases 1st is used only once but the 'wide ratio' has a much larger RPM drop between shifts. Myself I would avoid using 5th gear anyway as it isn't designed for the heavy loads associated with racing up hill. Top speed should be in 4th and adjusted by grear ratio and tire size.

 

This is by no means cast in stone as there are too many variables for that. This is a rough guide or at the most just something to think about. There are many other FS5W71B transmissions used on other years and models with even more choices of ratios from 4 and 6 cylinder deisels to gas, cars and trucks. The later 'B' has some small mods that make it stronger and last longer too.

[Hello710]

oh i see.well ok thanks man i appreciate the info.:)

[Bleach]

Avoid the turbo Z T5 5-speed mostly because you would need a custom driveshaft modified from the turbo Z driveshaft. The output splines are different.

[datzenmike]

Got that right. The clutch disc is different than the usual Nissan spline, they are longer than the reg 5 speed, wider in the bell and body, heavy and are not the 'world class' 5 spd they are thought to be, like in the Camaro or 5.0. Performance wise they are adequate for a 280zx turbo, (barely) and iffy in the 300zx. If there is anything good to say about them it's that they are cheap to rebuild. The front case (IIRC) can be swapped onto a Camaro/5,0/Firebird 5 spd. for a stronger tranny but Nissan already makes a better one for the non turbo 300zx.